1. Field of the Invention
The present invention concerns a method and an x-ray diagnostic device for generation of an image of a moving body region of a living subject that executes a movement due to respiration. X-ray projections of the body region of the subject, from which images of the subject are reconstructed with a computer, are acquired from different projection directions with a radiological measurement system that has an x-ray source and an x-ray detector.
2. Description of the Prior Art
In the generation of images of a body region of a living subject that executes a movement due to respiration, the desire frequently exists to generate images of the body region of the subject only in a specific phase of the respiration cycle. For example, it is known from U.S. Pat. No. 6,633,775 to synchronize the acquisition of an x-ray exposure with the respiration of a patient. For this purpose, the respiration cycle of the patient is detected and an x-ray exposure of the body part of the patient to be imaged is acquired at a specific degree of the inhalation of the patient.
In the acquisition of x-ray projections of a body region of a patient from various projection directions in x-ray computed tomography, for example with an x-ray computed tomography apparatus of the third generation in which a measurement system with an x-ray source and an x-ray detector rotates continuously around the patient, it is known to record the respiration cycle of the patient in parallel with the acquisition of the x-ray projections. The acquisition of the x-ray projections can thereby ensue during continuous table feed, i.e., continuous displacement of the patient on a patient table relative to a measurement system (spiral mode) or given a fixed position of the patient positioning table (sequence mode). Through the parallel recording of the respiration cycle of the patient, images of the body region of the patient can be specifically reconstructed in connection with the acquisition of the x-ray projections at selected phases of the respiration cycle of the patient. This method has the disadvantage that the patient is also exposed to x-ray radiation at the points in time of the respiration cycle of the patient at which no image information of the body region of the patient is required or, respectively, desired.